Need suggestions for Unlimited max speed internet plans, also I want to buy an iPhone 6s, can someone maybe suggest a nice contract purchase deal that gets me the best of both? iPhone 6s+unlimited full speed internet.

The best offer I have seen so far is from "true", 6s for 12.5k baht+1099baht per month that gives 300mbps unlimited internet with a 1 year contract. 1year contracts are fine I plan to stay here for atleast 1year.

Are there any better deals?

Also my company's HR told me AIS has some integration with the rabbit card that is used to bts, any information on how that works will be really helpful

What do you mean by 'unlimited max speed' - as in a plan that has unlimited data without any speed restrictions? I only know of DTAC offering mobile plans with no data limit (or downgrade to lower speed). For THB 1,999 / month you get maximum speed for unlimited data. If you're okay with 4Mbps you'll get that for as little as THB 699: http://www.dtac.co.th/en/postpaid/products/go-no-limit.html